Conventionally, there has been an interpolation apparatus for digital image signals, including a part that receives input image data, and extracts pixel data of a predetermined number of pixels around a particular pixel, and a part that generates pixel data of the particular pixel by interpolation using linear combination of a predetermined number of factors and the extracted pixel data of the predetermined number of pixels, wherein the factors are acquired using pixel data for acquiring the factors in advance through the least squares method such that a squared-sum of errors between interpolation values and true values becomes minimum (see Patent Document 1).
Furthermore, there has been a digital video signal converting apparatus that generates, from a first digital video signal, a second digital video signal having a larger number of pixels than the first digital video signal (see Patent Document 2).